U.S. patent number 6,099,496 [Application Number 09/164,008] was granted by the patent office on 2000-08-08 for catheter having a variable length shaft segment and method of use.
This patent grant is currently assigned to Medtronic AVE, Inc.. Invention is credited to William A. Berthiaume, Gregory Toso.
United States Patent |
6,099,496 |
Berthiaume , et al. |
August 8, 2000 |
Catheter having a variable length shaft segment and method of
use
Abstract
The invention relates to a catheter device and a method of use
to enable catheter exchange over a conventional length guidewire
without the use of a guidewire extension or exchange wire. The
catheter device includes an elongated inflation shaft having a
longitudinal inflation lumen, an extension shaft having a
longitudinal extension lumen coupled in fluid communication with
the inflation lumen, a balloon member disposed at the distal end of
the extension shaft and in fluid communication with the inflation
lumen, a guidewire shaft having a longitudinal guidewire lumen
which extends from the distal end of the balloon member, through
the balloon member and extension shaft, to the proximal end of the
extension shaft, and a variable length shaft coupled to the
proximal end of the extension shaft. The variable length shaft
comprises an elastomeric material which may be stretched from a
relaxed state of about 10 centimeters to a fully extended state of
about 140 centimeters.
Inventors: |
Berthiaume; William A. (Hudson,
MA), Toso; Gregory (Wilton, CT) |
Assignee: |
Medtronic AVE, Inc. (Santa
Rosa, CA)
|
Family
ID: |
22592577 |
Appl.
No.: |
09/164,008 |
Filed: |
September 30, 1998 |
Current U.S.
Class: |
604/102.02;
604/509; 604/510; 604/523; 604/528 |
Current CPC
Class: |
A61M
25/104 (20130101) |
Current International
Class: |
A61M
29/02 (20060101); A61M 029/00 () |
Field of
Search: |
;604/93,96,244,523,528,507,508,509,510 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Weiss; John G.
Assistant Examiner: Thissell; Jeremy
Attorney, Agent or Firm: Sterne, Kessler, Goldstein &
Fox PLLC
Claims
We claim:
1. A catheter device having a variable length guidewire lumen
adapted for use with a conventional length guidewire,
comprising:
(a) an elongated inflation shaft having a proximal end, a distal
end and an inflation lumen extending longitudinally
therethrough;
(b) an extension shaft having a proximal end, a distal end and an
extension lumen extending longitudinally therethrough, the
extension shaft proximal end being disposed adjacent the distal end
of the inflation shaft such that the inflation lumen and the
extension lumen are in fluid communication and form a continuous
passageway therethrough;
(c) a guidewire shaft having a proximal end, a distal end and a
guidewire lumen extending therethrough, the guidewire shaft
disposed longitudinally throughout the length of the extension
shaft, the distal end of the guidewire shaft extending beyond the
distal end of the extension shaft, and the guidewire lumen
dimensioned to slidably receive the guidewire;
(d) a balloon member having a distal end and a proximal end, the
proximal end of the balloon member being coupled to the distal end
of the extension shaft, the distal end of the balloon member being
coupled to the guidewire shaft adjacent the distal end of the
guidewire shaft, the balloon member defining an interior cavity in
fluid communication with the extension lumen; and
(e) a variable length shaft formed of an elastomeric material which
may be stretched from a relaxed state of about 10 centimeters to a
fully elongated state of about 140 centimeters, the variable length
shaft having a proximal end, a distal end and an interior surface,
wherein the distal end is coupled to the extension shaft and the
interior surface is substantially uniform at any length of the
shaft from the relaxed state to the fully elongated state.
2. The catheter device of claim 1, which further comprises an
anti-backbleed hub coupled to the proximal end of the variable
length shaft, the anti-backbleed hub having a central port
dimensioned to permit the inflation shaft and guidewire to pass
therethrough.
3. The catheter device of claim 1, which further comprises an
extension tube which provides a fluid communication passageway
between the inflation lumen and the extension lumen.
4. The catheter device of claim 1, wherein the distal end of the
variable length shaft is coupled about an outside surface of the
extension shaft, the variable length shaft extends longitudinally
in coaxial relation with the inflation shaft such that as the
variable length shaft is extended from the relaxed state to an
elongated state it encases the inflation shaft.
5. The catheter device of claim 1, wherein the inflation shaft is
formed from hypotube.
6. The catheter device of claim 1, which further comprises a
fitting coupled to the proximal end of the inflation shaft to
enable fluid communication between the inflation lumen and a source
of pressurized fluid.
7. A method for loading and unloading a balloon catheter device
having a variable length shaft segment over a conventional length
guidewire without the use of an exchange wire or a guidewire
extension, the method comprising the steps of:
(a) inserting a guiding catheter in a patient's vasculature;
(b) disposing an adapter at the proximal end of the guiding
catheter, such that the adapter is positioned outside the patient's
body;
(c) opening the adapter and inserting the conventional length
guidewire having a distal end and a proximal end into the guiding
catheter and advancing the distal end of the guidewire to a
treatment site within the patient's vasculature;
(d) loading the balloon catheter over the proximal end of the
guidewire and advancing the balloon catheter through the adapter
into the guiding catheter;
(e) coupling the balloon catheter to the adapter;
(f) maintaining the distal end of the guidewire in position across
the treatment site by gripping the guidewire at a position
proximate to the adapter;
(g) advancing the balloon catheter over the guidewire such that a
balloon member of the balloon catheter is across the treatment site
by pushing an inflation shaft of the balloon catheter toward the
adapter and thereby stretching the variable length shaft segment
from a relaxed state to a fully elongated state;
(h) unloading the balloon catheter by gripping the inflation shaft
proximate the adapter and withdrawing the inflation shaft through
the adapter until the variable length shaft segment is in the
relaxed state;
(i) decoupling the balloon catheter and the adapter;
(j) gripping the proximal end of the guidewire with one hand and
pulling the inflation shaft until the balloon catheter is withdrawn
from the patient; and
(k) gripping the guidewire at a position distal the balloon
catheter and pulling the balloon catheter off the proximal end of
the guidewire.
Description
FIELD OF THE INVENTION
The present invention relates to catheter systems employed in
intravascular procedures. More particularly, the present invention
relates to a catheter device and exchange system for facilitating
the exchange of catheters and/or guidewires, and for the transport
of such catheters and/or guidewires to a selected site within the
patient's vasculature without the need for guidewire extensions or
exchange wires.
BACKGROUND OF THE INVENTION
Catheters are widely used by the medical profession for a variety
of purposes and procedures. For example, catheters are commonly
used in the treatment of atherosclerotic lesions or stenoses formed
on the interior walls of the arteries. One procedure developed for
the treatment of such lesions or stenoses is coronary angioplasty.
The most commonly practiced angioplasty procedure is known as
percutaneous transluminal coronary angioplasty, or PTCA. According
to this procedure, a dilatation catheter having a balloon located
at its distal end is guided through the patient's vasculature such
that the balloon is positioned within the stenosis. When the
catheter is advanced through the patient's vasculature to the
treatment site, the balloon is in a deflated condition such that
the catheter has a minimum cross-section. The balloon is then
inflated one or more times to dilate the stenosis and open the
restricted area of the artery. Finally, the balloon is deflated and
the catheter is removed from the patient's vasculature.
Typically, the dilatation catheter is maneuvered through the
patient's vasculature with the use of a flexible guidewire having a
diameter of approximately 0.010 to 0.018 inches and a length of
about 180 centimeters. The distal end of the guidewire is extremely
flexible so that it may be routed through the convoluted arterial
pathway to the site of the stenosis. After the distal portion of
the guidewire is positioned across the stenosis, a dilatation
catheter having a lumen adapted to receive the guidewire is
advanced. over the guidewire until the balloon is positioned within
the stenosis. Alternatively, the guidewire and catheter may be
advanced together within the patient's vasculature to the treatment
site with the distal end of the guidewire protruding from the
distal end of the catheter.
The prior art includes three types of catheters for use with a
guidewire: "over-the-wire" catheters, "rapid exchange" catheters
and "fixed-wire" catheters.
A conventional over-the-wire catheter comprises a guidewire lumen
which extends throughout the length of the catheter. In use, the
guidewire is disposed entirely within the catheter guidewire lumen
except for its proximal and distal ends which protrude from the
proximal and distal ends of the catheter, respectively. A typical
over-the-wire balloon dilatation catheter is disclosed in Simpson
et al. U.S. Pat. No. 4,323,071.
Such over-the-wire catheters have many advantages attributable to
the full-length guidewire lumen. For example, these type catheters
have good stiffness and pushability for advancing the catheter
through the convoluted vasculature to the treatment site. Further,
the guidewire lumen provides a continuous conduit between the
proximal and distal ends of the catheter for transporting
radiocontrast dye to the treatment site or for enabling pressure
measurements. In addition, the full-length guidewire lumen allows
for the exchange of guidewires within an indwelling catheter,
should that be desired.
Despite these advantages, there are many undesirable complications
associated with the use of over-the-wire catheters. For example,
during a catheterization procedure, it may be necessary to thread a
catheter on or off an indwelling catheter, or exchange an
indwelling catheter for another catheter over an indwelling
guidewire. When advancing or withdrawing a catheter over an
indwelling guidewire, the physician must grip the proximal portion
of the guidewire extending outside the patient to maintain the
position of the distal portion of the guidewire across the
treatment site. However, the length of a conventional over-the-wire
catheter, typically on the order of 135 centimeters, is greater
than the length of the proximal portion of a standard guidewire
which protrudes out of the patient. Accordingly, it is necessary to
extend the guidewire a sufficient distance outside the patient so
that the physician may maintain his or her grip on the proximal
portion of the guidewire while threading an over-the-wire catheter
on or off an indwelling guidewire. The additional length of
guidewire needed may be provided by a guidewire extension which is
temporarily "linked" or attached to the proximal end of the
guidewire. Once the catheter has been threaded onto the guidewire
extension and advanced over the guidewire through the patient's
vasculature, the guidewire extension may be detached from the
guidewire.
Alternatively, an exchange wire, typically on the order of 300
centimeters, may be guided through the patient's vasculature such
that its distal portion is positioned across the stenosis. The
proximal portion of the exchange wire protruding out of the patient
is of sufficient length such that the physician may maintain his or
her grip on the proximal portion of the guidewire while advancing
the catheter over the guidewire. After the balloon located at the
distal end of the catheter is positioned within the stenosis, the
exchange wire may be removed from the guidewire lumen and
replaced with a shorter, easier to handle guidewire.
A number of alternative catheter designs have been developed in an
attempt to address these issues. One such design is the fixed-wire
catheter, which comprises a catheter having an internally fixed
guidewire or stiffening element. Catheters of this design are
readily maneuverable and relatively easy to position within the
patient's vasculature without the use of a separate guidewire.
However, because these catheters do not use a separate guidewire,
the administering physician is unable to maintain guidewire access
to the treatment site while removing the catheter. Thus, if it were
necessary to perform a catheter exchange, the physician must remove
the indwelling catheter and renegotiate the arterial pathway to the
treatment site with the replacement catheter.
Another alternate design is the "rapid exchange" type catheter and
guidewire system. Generally, a rapid exchange catheter includes a
guidewire lumen which extends along only a short shaft section near
the distal end of the catheter. Accordingly, when the catheter is
advanced over the guidewire, the guidewire is located outside the
catheter except for the short segment which passes through the
guidewire lumen at the distal end of the catheter. In use, a
conventional length guidewire is routed through the patient's
vasculature such that its distal end is positioned across the
treatment site. The distal end of the catheter is then threaded
onto the proximal end of the guidewire. Since the guidewire lumen
is relatively short, a rapid exchange catheter may be fully
threaded onto the guidewire without linking an extension wire or
using a long exchange wire. Similarly, when it is desired to
perform a catheter exchange procedure, the catheter may be
withdrawn over an indwelling guidewire without the use of a
guidewire extension or an exchange wire.
Although such a rapid exchange catheter system may eliminate the
need for an extension wire or a long exchange wire, it presents
significant disadvantages. For example, because these catheters
have a truncated guidewire lumen, they do not provide the same
stiffness and pushability as an over-the-wire catheter. Further, it
has been found that as these catheters are advanced or withdrawn
over a guidewire, the exposed portion of the guidewire may buckle
or bow relative to the catheter and possibly inflict damage to the
inner walls of the patient's vasculature. Furthermore, there exists
a significant risk of quidewire entanglement in procedures
involving multiple guidewires. In addition, unlike over-the-wire
catheters, it is not possible to exchange guidewires in an
indwelling rapid exchange catheter.
Therefore, there exists a need for an improved catheter device and
method of use which incorporates the benefits of both the
over-the-wire catheters and the rapid exchange catheters, but
without their attendant drawbacks.
OBJECTS AND SUMMARY OF THE INVENTION
In accordance with the present invention, a catheter device having
a variable length guidewire lumen is provided for insertion into a
patient over a conventional length guidewire. The catheter includes
an elongated inflation shaft having a longitudinal inflation lumen,
an extension shaft disposed distal to the inflation shaft, a
balloon member disposed at the distal end of the extension shaft, a
guidewire shaft having a longitudinal guidewire lumen which extends
from the distal end of the balloon member, through the balloon
member and the extension shaft, to the proximal end of the
extension shaft, and a variable length shaft coupled adjacent the
proximal end of the extension shaft. The extension shaft includes
an extension lumen having a proximal end in fluid communication
with the distal end of the inflation lumen and a distal end in
fluid communication with the interior of the balloon. The variable
length shaft comprises a stretchable tube formed of an elastomeric
material and having a length selectively variable from about 10
centimeters to about 140 centimeters.
When the catheter is threaded over an indwelling guidewire or when
the catheter is being exchanged with another catheter, the variable
length shaft is in a relaxed state having a length of about 10
centimeters. The distance from the proximal end of the variable
length shaft to the distal end of the guidewire shaft is
sufficiently short that the catheter may be threaded onto or
removed from the indwelling guidewire without the use of an
extension wire. Further, as the catheter is advanced over the
guidewire through the patient's vasculature, the variable length
shaft. stretches from its shortest length of about 10 centimeters
to its longest length of about 140 centimeters, thereby capturing
the entire length of the guidewire extending between the proximal
end of the catheter and the proximal end of the guidewire
lumen.
It is, therefore, a principal object of the present invention to
provide an improved catheter and guidewire system which enables
loading and unloading of the catheter over an indwelling guidewire
without the use of an extension wire, and the exchange of the
guidewire without compromising the position of the indwelling
catheter.
It is a further object of the present invention to provide an
improved catheter and guidewire system, wherein the catheter
includes a variable length shaft which provides an essentially
constant cross-sectional diameter when it is at any position
between a fully extended or fully retracted state.
It is a further object of the present invention to provide an
improved catheter and guidewire system, wherein the catheter
includes a variable length shaft which provides a smooth interior
surface when it is at any position between a fully extended or
fully retracted state.
Objects and advantages of the invention are set forth in part above
and in part below. In addition, these and other objects and
advantages of the invention will become apparent herefrom, or may
be appreciated by practice with the invention, the same being
realized and attained by means of instrumentalities, combinations
and methods pointed out in the appended claims. Accordingly, the
present invention resides in the novel parts, constructions,
arrangements, improvements, methods and steps herein shown and
described.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be further described, by way of example, with
reference to the accompanying drawings, wherein:
FIG. 1 is a cross-sectional view of the variable length shaft
catheter of the present invention with the variable length shaft in
its relaxed state;
FIG. 2 is a cross-sectional view of the variable length shaft
catheter tube of the present invention with the variable length
shaft in an elongated state;
FIG. 3 is a cross-sectional view of the variable length shaft
catheter shown in FIG. 2 along line 3--3;
FIG. 4 is a cross-sectional view of the variable length shaft
catheter shown in FIG. 2 along line 4--4; and
FIG. 5 is a cross-sectional view of the variable length shaft
catheter shown in FIG. 2 along line 5--5;
FIG. 6 is a cross-sectional view of the variable length shaft
catheter shown in FIG. 2 along line 6--6.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
It should be noted that while the following description will be
specifically in the context of coronary angioplasty dilatation
catheters, the invention is not so limited and is applicable to
other catheter assemblies and procedures. For example, it will be
understood that the present invention also applies to drug delivery
and/or stent delivery catheters.
Referring generally to the embodiments of the invention shown in
the accompanying drawings, wherein like reference numbers refer to
like parts throughout the various views, the basic principles of
the broadest aspects of the invention can be appreciated from FIGS.
1-6.
As shown in FIG. 1, the variable length shaft catheter of the
present invention, which is designated generally as 10, includes an
elongated inflation shaft 20, an extension shaft 30, a balloon
member 38, a guidewire shaft 40, and a variable length shaft
50.
The inflation shaft 20 includes a proximal end 22, a distal end 24,
and an inflation lumen 26 extending longitudinally throughout its
length. Preferably, inflation shaft 20 is formed from stainless
steel hypotube to provide the catheter with sufficient stiffness
and pushability. The proximal end 22 of inflation shaft 20 is
coupled to a fitting 28, which is designed to enable fluid
communication between inflation lumen 26 and a source of
pressurized inflation fluid (not shown). Preferably, fitting 28 is
in the form of a female luer fitting.
The extension shaft 30 includes a proximal end 32, a distal end 34,
and an extension lumen 36 extending longitudinally throughout its
length. As illustrated in FIGS. 1 and 2, the proximal end 32 of
extension shaft 30 is disposed adjacent the distal end 24 of
inflation shaft 20. Further, extension lumen 36 is coupled in fluid
communication with inflation lumen 26, such that inflation lumen 26
and extension lumen 36 form a continuous conduit enabling fluid
communication from the proximal end of inflation shaft 20 to the
distal end of extension shaft 30. Extension shaft 30 may be formed
from a flexible polymer material such as polyvinyl chloride,
polyethylene terephthalate or, preferably, high density
polyethylene. In a preferred embodiment, the distal end of
inflation shaft 20 and the proximal end of extension shaft 30 are
coupled via an extension tube 60. According to this configuration,
extension tube 60 provides a fluid communication pathway between
inflation lumen 26 and extension lumen 36. Preferably, extension
tube 60 is formed from stainless steel hypotube.
The balloon member 38 is disposed adjacent the distal end of
extension shaft 30. Balloon member 38 may be formed from polyvinyl
chloride, polyethylene, polyurethane or preferably, polyethylene
terephthalate. The interior of balloon 38 is in fluid communication
with the distal end of extension lumen 36.
The guidewire shaft 40 has a proximal end 42, a distal end 44, and
a guidewire lumen 46 extending longitudinally throughout its
length. Guidewire shaft 40 may be formed from a flexible polymer
material, such as polyvinyl chloride, polyethylene terephthalate
or, preferably, high density polyethylene. As illustrated in FIGS.
1 and 2, guidewire shaft 40 is longitudinally disposed within
extension shaft 30 and extends through balloon member 38, whereby
the distal end 44 of guidewire shaft 40 extends beyond the distal
end of balloon member 38. The distal end of balloon member 38 is
coupled to guidewire shaft 40.
Guidewire lumen 46 is dimensioned to slidably receive a standard
coronary angioplasty guidewire (not shown). As shown in FIG. 3, at
the proximal portion of extension shaft 30, guidewire shaft 40 and
extension tube 60 are disposed in a parallel arrangement, thereby
providing a side-by-side dual lumen cross section. As shown in FIG.
4, at the distal end of extension shaft 30, guidewire shaft 40
extends longitudinally through extension lumen 36, thereby
providing a coaxial dual lumen cross section. To this end, the
outer diameter of guidewire shaft 40 is dimensioned such that
extension lumen 36 forms an annular flow passage with sufficient
inflation flow capacity to permit acceptable balloon inflation and
deflation rates. Alternatively, it will be understood that
guidewire shaft 40 may be disposed in parallel arrangement with
extension tube 60 and extension lumen 36 to provide a side-by-side
dual lumen cross-section throughout the length of extension shaft
30.
The variable length shaft 50 comprises a tube having a proximal end
52 and a distal end 54. Variably length shaft 50 is formed of a
high elongation, resilient, elastomeric material, which may be
stretched from a relaxed state having a length of about 10
centimeters to a fully elongated state having a length of about 140
centimeters. Preferably, variable length shaft 50 is formed of an
unsaturated styrene/rubber material, e.g., Kraton.TM., which is
sold by Shell Chemical Co. As shown in FIGS. 1 and 2, the distal
end of variable length shaft 50 is sealingly coupled to the
proximal end of extension shaft 30. In a preferred embodiment,
variable length shaft 50 is coupled about the outside surface of
extension shaft 30 such that when it is in an extended state it
encompasses inflation shaft 20 (see FIG. 5). Alternatively,
variable length shaft 50 may be coupled to the proximal end of
extension shaft 30 such that it extends longitudinally in a
side-by-side arrangement with inflation tube 20. Further, the
catheter of the present invention may be adapted to have a
plurality of variable extension shafts for use in procedures
requiring multiple guidewires.
As illustrated in the preferred embodiment depicted in FIGS. 1 and
2, the proximal end of variable length shaft 50 is coupled to an
anti-backbleed hub 56. Anti-backbleed hub 56 functions to prevent
the backflow of fluids between the guiding catheter and catheter
10. Preferably, anti-backbleed hub 56 comprises a tubular member
having a flanged lip at its proximal end for abutment with the
Tuohy-Borst adapter. As shown in FIG. 6, anti-backbleed hub 56
includes a central port through which inflation shaft 20 and a
guidewire (not shown) can pass.
In addition, anti-backbleed hub 56 may be designed to act as a stop
or anchor which prevents the longitudinal movement of inflation
shaft 20 within variable length shaft 50. To this end,
anti-backbleed hub 56 is formed of a compressible material, such
that when the Tuohy-Borst adapter is closed and locked down on the
outer surface of anti-backbleed hub 56, anti-backbleed hub 56 is
radially compressed such that its inside surface grips and locks
down on inflation shaft 20.
Operation and use of the variable length shaft catheter of the
present invention is described as follows. A guiding catheter (not
shown in the FIGS.) is inserted into the patient's vasculature in a
conventional manner. A Tuohy-Borst adapter (not shown in the FIGS.)
is then disposed at the proximal end of the guiding catheter. Next,
the Tuohy-Borst adapter is opened to receive a standard length
guidewire. The guidewire is routed through the patient's
vasculature until the guidewire distal portion is positioned across
the treatment site. The Tuohy-Borst adapter is then closed such
that it locks down on the guidewire. With catheter 10 in a relaxed
state as shown in FIG. 1, catheter 10 is threaded over the
guidewire by inserting the proximal end of the guidewire into the
distal end of guidewire lumen 46. The catheter is then advanced
over the guidewire until the anti-backbleed hub 56 engages the
Tuohy-Borst adapter. Because catheter 10 is in a relaxed state and
has a minimum over-the-wire length, the proximal end of the
guidewire protrudes out the proximal end of guidewire lumen 46. The
Tuohy-Borst adapter is then closed until it locks down and is
securely coupled to the anti-backbleed hub 56.
Catheter 10 is advanced over the indwelling guidewire by holding
the proximal end of the guidewire and pushing the proximal end of
inflation shaft 20 in a direction toward the Tuohy-Borst adapter
until balloon member 38 is positioned across the treatment site.
Since the proximal end and the distal end of variable length shaft
50 are coupled to extension shaft 30 and anti-backbleed hub 52,
respectively, advancement of catheter 10 through the patient's
vasculature will cause variable length shaft 50 to stretch, and
thereby encase the portions of the guidewire and inflation shaft 20
extending between the distal end of extension shaft 30 and the
Tuohy-Borst adapter.
Accordingly, as catheter 10 is advanced over the guidewire, the
variable length shaft 50 and guidewire lumen 46 effectively form a
full-length guidewire lumen. As such, medications, saline or
radiocontrast dye, can be delivered to the treatment site by way of
injection into antibackbleed hub 52 and through the fluid
passageway created by variable length shaft 50 and guidewire lumen
36.
Once balloon member 38 has been positioned across the treatment
site, pressurized inflation fluid may be injected through fitting
28 by the use of a hand syringe or any other pressurizing device
known in the art (not shown in the FIGS.). The inflation fluid
passes through fitting 28, inflation lumen 26, extension tube 60
and extension lumen 36, before entering balloon member 38. The
inflation of balloon member 38 can be observed if radiographic
contrast liquid is used as the inflation fluid. As balloon member
38 is inflated with pressurized inflation fluid, it presses against
the treatment site and dilates the stenosis.
During a catheterization procedure, it may be necessary to exchange
the
indwelling catheter with another catheter having a different
feature. For example, it may be desired to follow a balloon
dilatation procedure with a drug delivery or stent delivery
procedure. Likewise, in the event the balloon on the indwelling
catheter is too small to sufficiently dilate the stenosis, the
administering physician may elect to exchange the indwelling
catheter with another catheter having a larger balloon. As provided
in the present invention, variable length shaft 50 of catheter 10
provides a means for catheter exchange without the use of an
extension wire or an exchange wire.
It is understood that during catheter exchange procedures, it is
desirable to maintain the position of the distal end of the
guidewire across the treatment site. To effect an exchange of
catheter 10, the administering physician holds the proximal end of
the guidewire in a fixed position. In addition, the physician grips
and pulls the proximal end of inflation shaft 20 such that the
catheter is withdrawn from the patient over the guidewire. As the
catheter is withdrawn from the patient, variable length shaft 50
retracts and is reduced in length until it reaches its relaxed
length. The Tuohy-Borst adapter is then opened and decoupled from
the anti-backbleed hub 56. While maintaining the position of the
distal end of the guidewire across the treatment site, the
administering physician removes the catheter 10 from the proximal
end of the guidewire. It will be understood that the effective
over-the-wire length of the catheter when variable length shaft 50
is in its relaxed state is sufficiently short to enable removal of
the catheter without the use of an extension wire. After the
original catheter is removed, a second catheter in the form of the
present invention may be threaded over the guidewire as described
above.
While only a few embodiments have been illustrated and described in
connection with the present invention, various modifications and
changes in both the apparatus and method will become apparent to
those skilled in the art. All such modifications or changes falling
within the scope of the claims are intended to be included
therein.
* * * * *